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loss of ozone in the lower stratosphere over Antarctica was first noticed in the 1970s by a research group from the British Antarctic Survey (BAS)
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two United States chemists predicted that a class of chemicals called chlorofluorocarbons (CFCs)
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Period: to
test
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Drop ozone layers
The ozone layer levels dropped dramaticaly -
an international meeting in Montreal created the world's first environmental convention.
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an international meeting in London voted for a strengthened Montreal Protocol under which CFCs, halons and other ozone-destroying chlorine compounds would be phased out by 2005
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the ozone hole over Antarctica was arguably the largest on record, with average ozone levels over Antarctica the thinnest ever observed. Polar stratospheric clouds (PSCs), which form during periods of